halothiobacillus neapolitanus carboxysomes sequester heterologous and chimeric rubisco specieshalothiobacillus neapolitanus carboxysomes隔离不同的和嵌合二磷酸核酮糖羧化酶的物种.pdfVIP

Halothiobacillus neapolitanus Carboxysomes Sequester Heterologous and Chimeric RubisCO Species 1 1 1 2 1 Balaraj B. Menon , Zhicheng Dou , Sabine Heinhorst , Jessup M. Shively , Gordon C. Cannon * 1 Department of Chemistry and Biochemistry, The University of Southern Mississippi, Hattiesburg, Mississippi, United States of America, 2 Department of Genetics and Biochemistry, Clemson University, Clemson, South Carolina, United States of America Abstract Background: The carboxysome is a bacterial microcompartment that consists of a polyhedral protein shell filled with ribulose 1,5-bisphosphate carboxylase/oxygenase (RubisCO), the enzyme that catalyzes the first step of CO2 fixation via the Calvin-Benson-Bassham cycle. Methodology/Principal Findings: To analyze the role of RubisCO in carboxysome biogenesis in vivo we have created a series of Halothiobacillus neapolitanus RubisCO mutants. We identified the large subunit of the enzyme as an important determinant for its sequestration into a-carboxysomes and found that the carboxysomes of H. neapolitanus readily incorporate chimeric and heterologous RubisCO species. Intriguingly, a mutant lacking carboxysomal RubisCO assembles empty carboxysome shells of apparently normal shape and composition. Conclusions/Significance: These results indicate that carboxysome shell architecture is not determined by the enzyme they normally sequester. Our study provides, for the first time, clear evidence that carboxysome contents can be manipulated and suggests future nanotechnological applications that are based upon engineered protein microcompartments. Citation: Menon BB, Dou Z, Heinhorst S, Shively JM, Cannon GC (2008) Halothio